Upon evading bullets during his last mission, an assassin decides to retire and daydreams about his future leisure. However, a mysterious woman thrusts a young boy at him, pleading him to save the child. Fourteen years later, instead of running an upscale art gallery, the assassin works in manual labor and raises a teenage son who grows increasingly aloof. Despite this, he takes pride in providing a content home for his adopted son until he discovers the reason for Ryuunosuke's odd behavior.